In the case of the previously known solutions of this type (US-A 2006/0201288 A1), provided between the handle and the gear head is an intermediate portion of the actuating arm that provides sufficient length of the handle for the torque that is to be applied in the pivoting screw-tightening movement. The intermediate portion is split over half its length, in order to allow it to perform a gap adjustment, which hinders the ease with which the gear head can be turned round, in order for example to ensure safe handling when undertaking a screw-tightening action with the gear head in such a position that its drive output element is in line with the actuating arm. Conversely, it is intended to make it easier to set the feature allowing the gear head to be turned round when the drive output element is aligned in the transverse position in relation to the actuating arm. This changing-over of the tool to the two, usually successive, screwing-up movements of a screw is unsatisfactory.
In addition, there are known screwdriving tools with universal joints provided at one end of an actuating arm, having on the actuating arm a transverse arm for applying the sufficiently great screw tightening force. The actuating arm itself in this case has a sheathing sleeve disposed on it. A genuine quick-action screwdriver position that can usually be switched conveniently to the so-called power-action screwdriver position, with the actuating arm directed transversely to the screw axis, is not envisaged and not possible.
It is an object of the invention to form a screwdriving tool of the type in question in such a way that it is optimally designed for two-handed actuation, irrespective of the angular position in which the reversible gear head is located in relation to the actuating arm. It is intended that, in every position of the gear head, both hands contribute to facilitating etc., the screwdriving operation.
This is achieved by a screwdriving tool with an actuating arm formed at one end as a handle portion and a freewheel gear arranged at the other end, and having a gear head which can be turned round at least through 90° into retained positions.
As a result of this configuration, the operator can use both hands—if need be even at the same time—to introduce a number of differently directed operating forces simultaneously into the screwdriving tool. It has been found that, in the quick-action screwdriver position, the tool can surprisingly be positioned and retained in a screwing-in direction so accurately with the hand grasping the sleeve that, with the other hand on the handle portion, it is possible by interrupted discrete gripping actions to give to the tool such great angular momentum that in the case of such tools, masses that are non-uniformly distributed on the circumference in the gear head act as centrifugal masses, which then maintain the screwing movement by self-acting further turning of the tool when the grip on the end of the handle is shifted, until it is grasped once again. Equally, the sleeve to be grasped by one of the hands helps to position the screwdriving tool. This applies both in the positive power-action screwdriver position and in the quick-action screwdriver position. Similarly, in the positive power-action screwdriver position, the actuating arm can be gripped around firmly with both hands without any strain on the hands, the hand that is gripping around the sleeve being able to carry out a height adjusting movement in relation to the securing hand, so that the hand grasping the handle portion can even safely let go and grasp.
U.S. Pat. No. 6,634,262 discloses a screwdriving tool with a gear head and a drive arm, the gear head forming a gear housing in which a freewheel or ratchet gear having an output rotational axis is disposed, a front side of the gear head having an output coupling in the form of a polyhedron, and the drive arm being pivotable about a pivot axis, which lies substantially transversely to the output rotational axis, from a quick-action screwdriver position, in which the drive arm lies in the output rotational axis, into a power-action screwdriver position, in which the drive arm extends substantially transversely to the output rotational axis, and the drive arm being fixed in both pivoted positions by detent means, the detent means being displaceable from a detent position into a release position by means of an actuating member associated with the drive arm. In the case of this screwdriving tool, the actuating means is a pin which can be displaced parallel to the pivot axis. This pin interacts with a detent ball, which interacts with detent recesses of a bearing extension of the gear head. The bearing extension is a narrow portion of the gear head that lies opposite from the square drive output element. This extension is passed through by a bearing screw.
DE 21 16 286 and DE 20 2006 007 090 U1 disclose screwdriving tools in which a ratchet gear has a square drive output element, the ratchet gear is disposed in a gear head and the gear head is fitted pivotably in a bifurcated opening of a drive arm.
DE 20 2004 000 843 discloses a screw wrench in which the gear head is located in a bearing fork of the drive arm. A handle disposed on the drive arm can be displaced along the drive arm. A similar screwdriving tool is described by US 2005/0166718 A1.
DE 499 786 discloses a tool with a pivotable lever. The lever is located in a lateral recess of a handle and can be pivoted by 90° about a pivot axis.
FR 2 865 677 likewise discloses a screwdriving tool. The drive arm is connected to a drive output blade in an axially fixed manner. The drive arm comprises two parts. One part can be pivoted about a pivot axis into a 90° position.
U.S. Pat. No. 6,976,411 discloses a screwdriving tool in which a pivot handle that protrudes at right angles from the output rotational axis is mounted on a drive arm.
U.S. Pat. No. 4,799,407 discloses a screwdriving tool in which a handle protruding at right angles is likewise provided, in order to increase the torque that can be applied to an output coupling. For this purpose, the screwdriver known from U.S. Pat. No. 3,475,999 also has a handle that is pivotable by 90°.
U.S. Pat. No. 4,541,310 describes a screwdriving tool with a drive arm which is connected to a gear head by means of an eccentric joint. The drive arm can be brought from a quick-action screwdriver position through 90° into a power-action screwdriver position.
In the case of the screwdriving tool known from U.S. Pat. No. 1,559,097, a pivoting handle that can be pivoted from a quick-action screwdriver position into a power-action screwdriver position is located in a recess in the handle. A similar solution is described by U.S. Pat. No. 3,342,229.
U.S. Pat. No. 1,601,767 describes a screwdriving tool with a drive arm which is fixedly connected to a gear head. A screwdriver handle may be fitted onto a drive projection of the gear head. A similar solution is described by U.S. Pat. No. 4,054,067.
It is an object of the invention to develop the screwdriving tool mentioned at the beginning advantageously in terms of its use.